From ae6a33f4b84f4d5e8c867d4a081215292e0ee967 Mon Sep 17 00:00:00 2001
From: Adam Wick <awick@uhsure.com>
Date: Wed, 4 Apr 2018 18:12:30 -0400
Subject: [PATCH] Support negation for signed numbers.

---
 src/cryptonum/signed.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/cryptonum/signed.rs b/src/cryptonum/signed.rs
index 1a46c51..1fd0e28 100644
--- a/src/cryptonum/signed.rs
+++ b/src/cryptonum/signed.rs
@@ -88,6 +88,30 @@ impl Ord for SCN {
 //
 //------------------------------------------------------------------------------
 
+impl Neg for SCN {
+    type Output = SCN;
+
+    fn neg(self) -> SCN {
+        if self.is_zero() {
+            self
+        } else {
+            SCN{ negative: !self.negative, value: self.value }
+        }
+    }
+}
+
+impl<'a> Neg for &'a SCN {
+    type Output = SCN;
+
+    fn neg(self) -> SCN {
+        if self.is_zero() {
+            self.clone()
+        } else {
+            SCN{ negative: !self.negative, value: self.value.clone() }
+        }
+    }
+}
+
 impl<'a> AddAssign<&'a SCN> for SCN {
     fn add_assign(&mut self, rhs: &SCN) {
         if self.negative == rhs.negative {